1. Field of the Invention
This invention relates to an air-conditioning system for a vehicle.
2. Description of the Prior Art
As disclosed, for instance, in Japanese Unexamined Patent Publication No. 3(1991)-28009, there has been known an air-conditioning system for a vehicle which operates either in an automatic control mode in which a control means automatically sets a plurality of air-conditioning factors such as the speed of the blower motor, the blow mode and the like and controls the air-conditioning system according to the air-conditioning factors automatically set, or in a manual control mode in which the air-conditioning factors are manually set and the control means controls the air-conditioning system according to the air-conditioning factors which are manually set. The air-conditioning system has a rotary control member which is rotated between a plurality of angular positions to set one of the air-conditioning factors to a desired value or a desired mode. A plurality of signs representing values or modes of said one air-conditioning factor are provided about the rotary control member and a mark such as an arrow is provided on the rotary control member. By rotating the rotary control member and setting the arrow at one of the signs corresponding to a desired mode or a value of said one air-conditioning factor when the air-conditioning system is operating in the manual control mode, said one air-conditioning factor is manually set to the desired mode or the desired value and the mode or the value thus selected is indicated by a telltale. When the rotary control member is rotated when the air-conditioning system is operating in the automatic control mode, the control is shifted to the manual control mode as far as said one air-conditioning factor.
In such a known air-conditioning system, there have been the following problems. That is, when the auto-switch is turned on and the control is shifted to the automatic control mode while the air-conditioning system is operating in the manual control mode, said one air-conditioning factor is automatically set to a value or a mode which is determined according to the operating condition of the air-conditioning system such as the temperature in the interior of the vehicle, the temperature outside the vehicle, the solar radiation entering the vehicle interior and the like, and the telltale corresponding to the value or the mode is lit independently from the angular position of the rotary control member. When the value or the mode at which the arrow on the rotary control member has been set differs from that indicated by the telltale, the driver will get embarrassed. Further when the rotary control member is rotated to change the value or the mode of said one air-conditioning factor while the air-conditioning system is operating in the automatic control mode, said one air-conditioning factor can be changed unexpectedly when the rotary control member is in an angular position indicated by the telltale during the automatic control mode. Further, in order to set said one air-conditioning factor to a desired value or a desired value, the operator must rotate the rotary control member watching the arrow on the rotary control member and the signs about it. This is troublesome.